Optimization of Solar Energy Using Solar Tracking ...

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energy. Solar energy has the sources of renewable energy. Its potential is 178 Billion MW, ... 1.43 KW of solar energy illuminates may one square meter which is ...
Optimization of Solar Energy Using Solar Tracking System 1

Alok Baranwal and 2Abhishek Dwivedi

1

Student, Dept. of Mechanical Engineering, Integral University, Dasauli, P.O. Bas-ha Kursi Road, Lucknow – 226026, India [email protected] 2 Assistant Professor, Dept. of Mechanical Engineering, Integral University, Dasauli, P.O. Bas-ha Kursi Road, Lucknow – 226026, India [email protected] ABSTRACT Solar energy is the most abundant stream of energy. It is available directly as solar isolation and indirectly as wind energy. Solar energy has the sources of renewable energy. Its potential is 178 Billion MW, which is about 20,000 times the world’s demand. Sun sends out energy in the form of electromagnetic radiation. The solar cells receive the solar energy. The solar cells operate on the photo-electric energy by using solar cells principle. The energy from the photo voltaic cells is used to switch on the lights. At present solar electric power generation systems are having fixed solar panels whose efficiency of generation is less. The aim of the project is to introduce the SOLAR TRACKING to the existing fixed solar panels, thus we are maintaining the constant maximum power output. Thus by using this tracking system we can increase the conversion efficiency of the solar electric power generation. For this tracking purpose we use a sensor and the input from the sensor is given to the micro controller and according to the program the panel is fixed to the maximum intensity position. Here we are using PIC micro controller. The 16F877 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of Flash Programmable and Erasable Read Only Memory (PEROM). The opto-coupler used is to provide isolation between the micro controllers to the sensor circuits. Keywords-Solar energy, Solar cell, solar tracking, PIC.

1.

INTRODUCTION

Sun is the primary source of Energy. The earth receives 16 x 1018 units of energy from the sun annually, which is 20,000 times the requirement of mankind on the Earth. Some of the Solar Energy causes evaporation of water, leading to rains and creation of rivers etc. Some of it is utilized in photosynthesis which is essential for sustenance of life on earth. Man has tried from time immemorial to harness this infinite source of energy. But has been able to tap only a negligibly fraction of this energy till today. The broad categories of possible large scale applications of solar power are the heating and cooling of residential and commercial buildings. The solar cell receives the solar energy. The solar cells operate on the principle of photovoltaic effect, by using solar cells. Basically the cells are placed in an open and fixed manner.

2.

SOLAR ENERGY SCENARIO

Drastic changes in energy conversion system are anticipated due to shortage of conventional fuels. Fuel deposit in the world will soon deplete by the end of 2020. Fossil fuel scarcity will be maximum. The main reasons for the above are due to increasing demand for electricity, rising population, rapid advance in technology

A. Solar Energy Options Solar energy has the greatest potential of all the sources of renewable energy and it will be one of the most important source of energy especially when other sources in the country have depleted. Solar Energy can be a major source of power. Its potential is 178 billion MW which is about 20,000 times the worlds demand. The energy radiated by the sun on a bright sunny day is approximately 1kw/m2 Photovoltaic cell is an alternate device used for power generation which converts suns radiation directly into electrical power. B. General Concept In 1968 Dr. Peter Glaser in the U.S. Published an idea that centered on the fact that in orbit close to earth, 1.43 KW of solar energy illuminates may one square meter which is considerably greater and one more continuous than an anyone square meter on the Earth which, even when perpendicular to the sun can receive only a maximum of 1 kw. His idea was, converting sunlight to electricity to convert to a radio frequency signal and beamed down to the earth carrying significant levels of energy. This electricity is by establishing a very large array of solar cells in geostationary orbit. A receiving antenna station on the earth would convert this radio frequency back into an alternate current which would be fed into a local grid. 3.

Principles of operation Solar photovoltaic The solar energy can be directly converted into electrical energy by means of photovoltaic effect, i.e. conversion of light into electricity. Generation of an electromotive force due to absorption of ionizing radiation is known as photovoltaic effect. The energy conversion devices which are used to convert sunlight to electricity by use of the photovoltaic effect are called solar cells. Photo voltaic energy conversion is one of the most popular nonconventional energy source. The photovoltaic cell offers an existing potential for capturing solar energy in a way that will provide clean, versatile, renewable energy. This simple device has no moving parts, negligible maintenance costs, produces no pollution and has a lifetime equal to that of a conventional fossil fuel. Photovoltaic cells capture solar energy and convert it directly to electrical current by separating electrons from their parent atoms and accelerating them across a one way electrostatic barrier formed by the function between two different types of semiconductor material. 4. Solar Tracking Controlling System Solar tracking system has multiple functions and uses two motors as the drive source, conducting an approximate hemispheroidal 3-D rotation on the solar array (see Figure 1). The two drive motors are decoupled, i.e., the rotation angle of one motor does notinfluence that of the other motor, reducing control problems. Additionally, the tracker does not have the problems common to two axis mechanical mechanisms (that one motor has to bear the weight of the other motor). This implementation minimizes the system’s power consumption during operation and increases efficiency and the total amount of electricity generated.

Figure 1 Solar Tracking Array Structure

5.

SOLAR TRACKING METHOD

Figure 2: Solar Tracking Method This solar tracking method use solar position Algorithm to “see” the sun and position (i.e. Azimuth and Zenith) and according to this it changes very dynamic fashion to the optimal position. For more efficiency this solar tracking method work in the “high DNA of sun”(brightest sky) approach. Thus, unwanted movement in the “search of the sun” of the due to GPS fault that result expected, leading to increased power consumption, mechanical wear and decreased overall feasibility. The precision range of tracked systems is between 0.01 degrees. Since concentric PV and heat devices exhibit only a very small deviation in efficiency with tracking accuracy. Relatively low technical complexity, they are applied mainly for industrial PV and concentric solar heat tracking .

Figure 3: Flow Chart of system Figure 3 show that system flow diagram in which first step capturethe frame from GPS it gives UTC time , Latitude Longitude, N/S and E/w indicator ,used satellite , Horizontal Dilution of Precision , MSL Altitude.

6.

SOLAR TRACKING SYSTEM

Solar energy is the oldest primary source of energy. It is clean, renewable and abundant in every part of the world. Almost all energies are derived from solar energy. However it is possible to convert solar energy into mechanical or electrical energy with adequate efficiency. Sun tracking systems are designed in a way to track the solar azimuth angle on a single axis or to track the solar azimuth and zenith angles on two axes. For the purpose of clarity, the east-west of the tracker will be called the “horizontal tracking” while the angular height tracker will be referred to as “vertical tracking”. In the literature based on the previous studies, it was observed that sun tracking systems provided a significant increase in the amount of energy produced (Zogbit and Lap laze, 1984).

The most commonly used system in sun tracking systems is controlling the motor that moves the panel by evaluating the signals received from the photo sensors placed on the PV panel ends through several control systems (Abdalah, 2002).Based on the tracking principles, we can classify the controlling process into three processes namely passive control unit, microprocessor control unit and electro –optical control unit. Passive control unit isbasically a system conducted without any electronic device. The microprocessor control unit is more accurate .Electro optical control unit tracks the sun by a solar detecting device that is sensitive to solar radiance Photosensors that are found on PV panel ends produce a signal relative to the sun light that falls on them. Changes according to the movement of the sun occur in the signals produced by photosensors. These different signals, which reach the control system, are evaluated and the required instruction signal is sent to the motor, which moves the PV panel. The panel moves according to this control signal and the movement of the PV panel stops at the position where it directly faces the sun, when the signals from both photosensors reach the same value. In these photosensor systems, unstable states may exist under overcast and partly cloudy weather conditions when the photosensors do not see the sun . According, it is anticipated that PV systems will become one of the main energy recourses to fulfill the global energy requirement by the end of this century. Solar panels are usually set up to be in full direct sunshine at the middle of the day facing south in the Northern Hemisphere or north in the Southern Hemisphere. Therefore morning and evening sunlight hits the panels at an acute angle reducing the total amount of electricity which can be generated each day. Solar cells are systems that are composed of semiconductor materials and which convert solar energy directly into current. The amount of electrical energy which will be obtained is directly proportional to the intensity of sun light that falls on the photovoltaic (PV) panel. When light falls on the device the light photons are absorbed by semiconducting material and electric charge carriers are generated. The relation between incident photon energy and frequency is W= h.ν, where h= Planck constant and ν= frequency. Silicon is the most abundant element available on the earth surface and mostly of the solar cells fabricated using them. The equivalent circuit of the solar cell is shown in Fig. 4. The current supply Iphrepresents the electric current generated from the sun beaming on the solar cell. Rjis the non-linear impedance of the P-N junction. Djis a P-N junction diode, Rshand Rsrepresent the equivalent line-up with the interior of the materials and connecting resistances in series. Usually in general analysis, Rshis large, and the value of Rsis small. Therefore in order to simplify the process of analysis, one can ignore Rshand Rs. The symbol Ro represents the external load. I and V represent the output current and the voltage of the solar cell, respectively.

Figure 4 Solar cell equivalent circuit From the equivalent circuit, and based on the characteristics of the P-N junction, equation (1) presents the connection between the output current Iand the output voltage V: I= npIph - npIsat[exp(qV/kTA ns)-1] (1) where nprepresents the parallel integer of the solar cell; ns represents the series connected integer of the solar cell; q represents the contained electricity in an electro (1.6×10− 19 Columbic); k is the Boltzmann constant (1.38×10− 23 J / K); T is the temperature of the solar cell (absolute temperature K); and A is the ideal factor of the solar cell (A = 1 ~ 5). The current I sat in equation (1) represents the reversion saturation current of the solar power. Further, I sat can be determined by using the following formula: Isat=Irr[T/Tr]3exp[qEGap/KA(1/Tr-1/T)]

(2)

Trrepresents the reference temperature of the solar cell; Irris the reversion saturation current at the time when the

solar cell reachesits temperature Tr; and EGapis the energy needed for crossing the energy band gap for the semiconductor materials. A solar tracker is basically a device on to which solar panels are fitted which tracks the motion of the sun across th e sky ensuring that the maximum amount of sunlight strikes the panels throughout the day. After finding the sunlight, the tracker will try to navigate through the path ensuring the best sunlight is detected. It was observed that at 37.6 degrees latitude 32.5% more energy is obtained from the PV panels which tracks the sun. The sun tracking PV systems are more economical and they will decrease the investment costs. The systems which were implemented in this study can easily be used in sun tracking systems of the PV panels. However, when it is considered to increase the sensitivity of the tracking system, it will be more feasible to use high-bit analog modules. Sun tracking can increase the power output for PV solar power plants by about 25% to 40%, depending on the geographic location. A single axis tracker will increase power output by 26%, while a dual axis tracker increases power by 32%. Single axis trackers follow the sun from east to west, while two axis trackers also track the sun altitude (up/down) Since the sun moves across the sky throughout the day, in order to receive the best angle of exposure to sunlight for collection of energy, a tracking system is often incorporated into the solar arrays to keep the array pointed towards the sun. To build an efficient solar tracker system sensor, Lab view software, motor and PV panels are required. The sensor is used to measure the temperature of two directions (East and West). The Light Dependent Resister (LDR) and Photo-diode can be used as a sensor. Second is the Lab view software where the system is modeled. Third is the motor which moves the panel connected to it and lastly the PV panel which is coupled mechanically with the shaft. 7.

WORKING PRINCIPLE

The circuit of the solar tracking system is dived into two parts. First part is dealing about sensors and other logical blocks which control the stepper motor and second part is nothing but a design of stepper motor, which moves the panel in appropriate position. And the working principle of the circuit is discussed below:  In this circuit the source of solar energy is assumed as numeric value in Lab view software.  Two sensors are placed in two directions are joined with the input values with the help of wire. Here two thermometers are used as a sensor.  The outputs of the thermometers are connected to meters which show the intensity of two directions.  The output of the thermometer is multiplied with a value of 2400.  After measuring the intensity of two directions, it is necessary to compare each other.  First the comparison is made between east intensity of the light and the west intensity of light with the help of comparison component Less (